Field of the Invention
The present invention relates to an end face grinding method and an end face grinding device. More particularly, it relates to an end face grinding method to perform dry type grinding of an end face of a honeycomb structure, and an end face grinding device.
Description of the Related Art
Heretofore, a honeycomb structure made of ceramics (hereinafter simply referred to as “the honeycomb structure”) has broadly been used in a use application such as a car exhaust gas purifying catalyst carrier, a diesel particulate removing filter, or a heat reservoir for a burning device. The honeycomb structure is manufactured by preparing a forming material (a kneaded material), extruding the material into a desirable honeycomb shape by use of an extruder, followed by raw cutting, drying and finish-cutting, and then subjecting the material to a firing step of firing the material at a high temperature. The honeycomb structure includes a plurality of polygonal cells defined by latticed cell partition walls.
In the firing step, a honeycomb formed body is mounted on a shelf plate in a state where one end face of the honeycomb formed body is directed downward, and the honeycomb formed body is introduced together with the shelf plate into a firing furnace. At this time, to prevent the honeycomb formed body from being adhered to the shelf plate, a firing support plate called “a setter” is interposed between the shelf plate and the honeycomb formed body. As to this setter, a cut piece of the honeycomb structure obtained by firing the honeycomb formed body is used as the honeycomb formed body firing setter, but when the setter is repeatedly used, chipping occurs. Therefore, a press-molded and fired ceramic raw material called “a pressed setter” is used, and is therefore repeatedly usable. Such setters are generically called “a firing setter”. In the present description, the extruded body before fired is called “the honeycomb formed body”, and the fired body is called the honeycomb structure.
The extruded honeycomb formed body causes a firing shrinkage along a longitudinal direction of cells and a direction orthogonal to the cell longitudinal direction in the firing step. Consequently, when the honeycomb formed body is mounted on the above firing setter and introduced into the firing furnace, a shift occurs between an upper surface of the firing setter and a lower end face of the honeycomb formed body due to the firing shrinkage of the honeycomb formed body. Therefore, in a case where a partition wall thickness of the honeycomb formed body is small and the body is easy to be deformed or a case where a product diameter of the honeycomb formed body is large and an absolute shrinkage amount due to the firing shrinkage is large, the cell partition walls of the end faces of the honeycomb structure are deformed by the above shift.
Consequently, in a case where the honeycomb formed body including the thin cell partition walls is fired, a raw setter for firing (hereinafter simply referred to as “the raw setter”) obtained by slicing an unfired honeycomb formed body made of the same material as in the honeycomb formed body is used in the firing step. As to the raw setter, a firing shrinkage difference between the raw setter and the honeycomb formed body as a firing object is not made during the firing, and the raw setter can cause the firing shrinkage along the longitudinal direction of the cells and a cross sectional direction orthogonal to the longitudinal direction of the cells at the same timing and the same ratio as in the honeycomb formed body.
In consequence, the above shift does not occur between the honeycomb formed body and the raw setter in the firing step, and it is possible to solve problems such as defects of the end face cell partition walls. However, the raw setter can only be used in one firing step, and is disposable. Therefore, as compared with the repeatedly usable firing setter, there is the problem that manufacturing cost of the honeycomb structure increases.
A method is known in which, for the purpose of suitably finishing end faces of a honeycomb formed body, the honeycomb formed body is conveyed between a pair of cup type rotating grinding wheels whose grinding surfaces face each other, along a direction orthogonal to a rotating direction of the cup type grinding wheels, to cut deformed portions of cell partition walls which are generated in the end faces of the honeycomb formed body, followed by firing (see Patent Document 1). Alternatively, for the purpose of removing the deformation of cells and chipping of the partition walls in the end faces which is generated in cutting a raw material, the end faces of a fired honeycomb structure might be ground and processed. A method is known in which a cup type grinding wheel is disposed on each of the end faces of a mounted and fixed honeycomb structure so that a grinding surface of the cup type grinding wheel is substantially parallel to the end face, and the rotating cup type grinding wheel is brought close to the end face at a predetermined grinding wheel feeding speed to grind the end face (see Patent Document 2).
[Patent Document 1] JP-A-2008-12786
[Patent Document 2] JP-A-2006-281039